“Top-down planning” is the process of identifying an element of a project or endeavor, and creating a hierarchy of sub-elements by breaking down the identified element into a number of sub-elements, breaking down a sub-element into a number of further sub-elements, etc. Sub-elements are required to be completed in order to complete the identified element, and a summation of the hierarchy of sub-elements is equal to the identified element. Top-down planning is frequently used for budget distribution, work distribution, etc. For example, an overall project may be to construct a bridge on a budget of $100,000,000. Top-down planning breaks down the overall project into the individual steps required to construct the bridge, such as constructing 10 pillars, transporting 100 concrete slabs, placing all the concrete slabs in the correct places, etc. The $100,000,000 budget is also broken down and associated with each individual step that needs to be accomplished. For example, the construction of the 10 pillars is associated with a cost that is a portion of the $100,000,000 budget, the transportation of the 100 concrete slabs is associated with a cost that is another portion of the $100,000,000 budget, etc.
A form of planning that is complementary to “top-down planning” is “bottom-up planning.” “Bottom-up planning” is where smallest elements are defined first, and then grouped into bigger elements, etc. Thus, an entire project or endeavor is defined from the smallest element upwards. In many practical scenarios, bottom-up planning and top-down planning results in different planning metrics. In these scenarios, it is typical to compare the bottom-up plan and the top-down plan visually, side-by-side, and consolidate the two plans (or portions thereof).